With the summer well and truly here, what better time to get started on that garden decking project that has been in the back of your mind for weeks? And if you’re reading this in the colder months? All the more reason to read up and get prepared for the next time a dry and bright day rolls around. In this straightforward guide, we’re going to teach you how to lay
Understanding your options: ground level vs raised decks
Before we dive into the main tutorial, there’s something we need to clear up so you can best consider your options.
There are two key methods for laying garden decking:
Ground level decking
Laying decking directly on the ground, so grass, soil or pre-prepared concrete slabs is what our tutorial will be covering for the most part. This method is ideal for flat, even surfaces like well-maintained grass, and is generally quicker and more cost-effective.
Raised decks on risers
The second method offers extra durability and stability; it’s more suited to uneven terrains or areas prone to moisture and involves more time and expense.
Both methods will ensure you build a solid garden deck that provides wonderful long-lasting sturdiness for whatever its envisioned purpose – from creating a walkway next to a garden pond to a platform for al fresco dining. However, for most DIY enthusiasts and homeowners looking for simplicity, laying decking on grass often proves to be the preferred choice due to its straightforward installation and natural integration with the surroundings.
What you will need
Before you begin, gather the necessary tools, equipment, and protective gear to ensure a smooth installation process.
Materials
- Timber decking boards and joists
- Gravel
- Ready-to-pour concrete, slabs and damp-proof course (optional)
- Rails, spindles, balusters
Tools and equipment
- Tape measure: Essential for accurate measurements of the decking area.
- Spirit level: Ensure your decking is level for safety and aesthetics.
- Garden spade, hoe or strimmer: For clearing existing turf and preparing the ground.
- Wheelbarrow: Useful for transporting materials like gravel, cement, or decking boards.
- String and pegs: Helps to establish straight lines and ensure alignment of the decking.
- Pencil and marking tools: For marking cut lines and framing positions.
- Saw: A circular saw or handsaw for cutting decking boards to size.
- Drill and screwdriver bits: Needed for fixing decking boards and constructing the frame.
- Hammer: For driving in nails or securing fixings.
- Adjustable wrench or spanner: Used for tightening bolts or nuts on the decking frame.
- Decking screws and nails: To hold the boards together.
- Carpenter’s Square: Helps to ensure corners are square during construction.
Protective gear
- Protective gloves: Essential for handling materials, decking boards and mixing cement, if required.
- Safety goggles: Protect your eyes from debris, especially when cutting or drilling decking timber.
- Dust mask: Choose one suitable for cutting timber to protect against dust inhalation.
- Earplugs: Use when operating power tools to protect your hearing, ensuring they fit comfortably with other safety wear.
- Knee pads: Provide cushioning and support during tasks that require kneeling down.
Ground preparation: Setting the stage for success
Preparation matters. We hear this over and over again. And every competent DIYer agrees.
However, not all prep is created equal, and this is important to recognise, so your efforts of installing your decking on grass aren’t wasted and your gorgeous new outdoor surface lasts as long as it should.
Assess the site
Begin by assessing the area where you plan to install the decking. Ensure the ground is relatively flat and free from any large stones or debris that could impact the stability of your deck, and – of course – that you have permission to put one in place. You might also want to weigh up aesthetic considerations – for example, will placing your decking near a fence or some shrubbery make your garden feel more private?
Clear the area
Once you’ve found the ideal spot, mark out the site using the pegs and string. With the string line accurately in place, you can begin to remove any existing turf or vegetation using a spade or another suitable garden tool of your choice. It’s absolutely crucial to create a clean and level surface for the decking boards to rest on, so don’t speed past this bit!
Use your spirit level along with a straight edge (a deck board will do) to keep tabs on how straight and level your plot is. Not happy with it? Carefully, level out any issues and check once again.
Create a solid foundation
With the basics of the ground readied, it’s time to choose what surface your ground-level deck is going to be placed on. Here we come to a crossroads; you can either:
- add concrete slabs for additional stability
- or lay the decking straight onto the prepared ground.
If you choose to add concrete slabs
Calculate where the concrete pads are needed and dig holes approximately 150mm square and 150mm deep at intervals of 1.2m around the deck area – it’s crucial you get these even.
Then, with these ready, fill each hole with quick-drying, ready-to-use concrete until just above ground level. Use a spirit level and straight edge to ensure all slabs are level with each other. You can adjust as necessary by levelling off the highest points with a brick trowel while the concrete is still semi-dry.
Install a weed barrier
To prevent unsightly weeds from growing up through your deck, you’ll need to lay a weed barrier fabric over the newly cleared and levelled area. This will help maintain the integrity of your deck over time, and keep it safer for young ones who may trip on overgrown plants.
If you’re installing the decking directly on the ground, this will be easy. Simply cover the designated area with the sheet material and weigh it down with 40-50mm of gravel
For those using concrete slabs, it’s a little more complicated. When the poured concrete has completely hardened, cover the entire area with weed control fabric, making cut-outs for the slabs. Then, add a layer of gravel 40-50mm deep.
Cut and lay squares of damp-proof course material between the concrete pads and the deck joists. This provides additional protection against moisture, extending the lifespan of your deck structure. Finally, lay concrete pads or paving slabs at intervals where the decking frame will sit. This provides essential support and prevents sinking, especially in areas with soft soil or frequent rainfall.
Decking preparation
Now you understand how to prepare for laying your decking on grass, we can move swiftly into the final leg of the tutorial.
Timber preparation
Before proceeding with installation, it’s important to ensure that your decking is properly treated. Timber decking boards are typically treated with preservatives to protect against rot, fungal decay, and insect infestation.
The treatment process, known as pressure treatment or tanalising, involves impregnating the wood with chemicals (e.g., Tanalith® E) under high pressure to ensure deep penetration. If your boards haven’t undergone this preparation, make sure to buy a wood preservative and apply it as directed on the packaging.
Sub-frame construction
Construct a sturdy frame using treated timber joists, ensuring they are level and securely fixed into place. This frame will serve as the base onto which your decking boards will be secured.
Creating a sturdy sub-frame is crucial for the stability and longevity of your decking. Here’s how to do it right:
Step 1: Plan around existing features
When planning your deck, consider existing features like trees. Instead of removing a tree, integrate it into your deck design. Frame the trunk by positioning the joist off-cuts between inner joists, secured with coach screws at each end. This allows the tree space to grow and sway naturally. Remember, different tree species grow at varying rates, so research beforehand to accommodate growth.
Step 2: Dry run and board placement
Before committing to construction, do a dry run by laying out the joist frame and placing deck boards on top. Ensure you leave the recommended expansion gaps—5 to 8mm along the length and 3mm at the ends for timber boards, and 6mm uniformly for solid composite boards. Use a gauge screw or wood off-cuts as spacers to maintain consistent gaps for a polished finish.
Step 3: Measure and cut
Measure the deck frame accurately and cut the timber joists to size. Double-check your measurements to avoid errors before proceeding.
Step 4: Preparing for drilling
On the outer joists of the frame, make two pencil marks at each end, aligned with the centre of the adjoining outer joist. These marks indicate where the coach screws will go – that’s eight marks in total, two at each corner of the outer frame.
Step 5: Drilling and countersinking
Use a flat wood bit to drill recesses at each pencil mark, deep enough to accommodate the screw heads flush with the joist surface. These countersunk holes ensure a tidy finish.
Step 6: Pilot holes for coach screws
Switch to a thinner drill bit than the coach screw’s shank to drill pilot holes through the recesses into the adjoining outer joist. Pilot holes prevent wood splitting and guide the screws for accurate placement.
Step 7: Securing the frame
Secure the outer frame by inserting and tightening coach screws with a drill driver or socket and ratchet. It may be easier to tackle one corner at a time for better control.
Step 8: Attaching inner joists
With the outer frame secured, repeat the process to attach the inner joists. Use two coach screws at each end of every inner joist, ensuring they are securely fastened to provide complete structural integrity.
Installing decking boards on grass step-by-step
With the subframe securely in place, it’s time to transform your prepared groundwork into a functional outdoor living space with the installation of decking boards. This step-by-step guide will ensure a smooth and professional finish to your project.
1) Laying the first board
Start by placing the first decking board flush against the outer edge of the subframe. Use galvanised decking screws to secure the board to the joists, ensuring a gap of 5-8mm between each board for expansion and drainage.
2) Continuing across the deck
Lay subsequent boards parallel to the first, using spacers or offcuts of timber to maintain consistent gaps. Ensure each board is securely fixed to the joists, checking alignment with a string line or carpenter’s square for a straight finish.
3) Cutting and trimming
Use a circular saw or handsaw to cut boards to size where necessary, ensuring clean, straight cuts for a professional appearance. Boards may need trimming around obstacles like trees or posts, following the guidelines for accommodating natural growth and movement.
4) Fixing additional features
If your design includes handrails, spindles, or balustrades, install these components as per manufacturer instructions. Secure handrails to posts using appropriate fixings, ensuring a sturdy and safe railing around your deck perimeter.
5) Securing edging and trim
Complete the look of your deck by adding edging boards or trim along the outer edges. This not only enhances aesthetics but also provides a finished aesthetic while concealing the subframe components.
6) Applying finishing treatments
Consider applying a protective finish or stain to your decking boards to enhance durability and aesthetics. Choose a product designed for exterior wood and follow manufacturer guidelines for application and maintenance.
7) Final checks and adjustments
Once all boards, handrails, and finishing touches are in place, conduct a thorough inspection. Ensure all fixings are tight, boards are level, and gaps are consistent. Make any necessary adjustments before enjoying your newly completed deck.
See, it wasn’t that hard!
We hope that this guide has shown you that the process of laying decking on grass isn’t so hard. It just takes a bit of time, effort and patience to see the project through. So, what do you say? Are you ready to give it a spin?
